1. Field of the Invention
The present invention relates to decorative panels and, more particularly, to an abrasion resistant laminate for use as a decorative panel. The abrasion resistant laminate is preferably a low pressure laminate. The laminate has preferably a printed decorative pattern, but can have a solid color. In addition, the present invention relates to a process for manufacturing such an abrasion-resistant laminated panel.
2. Description of Related Art
Decorative panels have been used to produce kitchen and bath cabinets, office furniture, store fixtures and recreational furniture. For many years, decorative furniture components were made by laminating a high pressure laminate to wood panel substrate, such as plywood or particleboard. The glue line lamination occurred either before or after the furniture was assembled. Within the past twenty-five years, a low pressure laminate has become available. Such low pressure laminates are manufactured by directly laminating the decorative sheet to the substrate under heat and pressure.
Conventionally, high pressure decorative laminates have been made by stacking and curing, under heat and pressure, a plurality of layers of paper impregnated with synthetic thermosetting resins. Normally, the assembly consists of three to eight core sheets. The assembly has from the base upward (1) phenolic resin impregnated Kraft paper, (2) a decor or decorative sheet impregnated with melamine resin, and (3) for printed patterns, an overlay sheet which, in the laminate, is almost transparent and provides protection for the decor sheet.
Some improvements are described in U.S. Pat. No. 4,255,480 and U.S. Pat. No. Re. 32,152, both to Scher, et al. For example, U.S. Pat. No. 4,255,480 discloses manufacturing decorative laminates having an ultra-thin, protective coating deposited as the uppermost layer of the decor sheet to enhance abrasion-resistant properties. The decor sheet is coated with an ultra-thin layer of a mixture of an abrasion-resistant hard mineral and a binder material. The hard mineral has a particle size of 20 to 50 microns.
Background patents of interest are U.S. Pat. Nos. 3,373,070 and 3,373,071 to Fuerst. The Fuerst technique is to impregnate the decor sheet first with plain melamine resin, and then apply a thick coating to the surface of the impregnated sheet using a relatively viscous mixture of 2,000-60,000 centipoise.
U.S. Pat. No. 3,975,572 to Power employs an acrylic resin-melamine/formaldehyde resin composition which, like the coating in the Fuerst patents, is applied over the already impregnated decor sheet, after the saturated decor sheet has been dried.
U.S. Pat. No. 4,322,468 to Raghava uses a special coating composition of a fully hydrolyzed polyvinyl alcohol modified melamine-formaldehyde resin.
U.S. Pat. No. 4,713,138 to Ungar et al. discloses a method of providing a paper facing sheet for use as the uppermost sheet in the manufacture of abrasion resistant decorative laminates. The process includes the step of effecting coating and impregnating in essentially one step. According to this patent, the laminated panel has an abrasion resistant composition deposited in an ultra-thin layer.
U.S. Patent No. 4,880,689 to Park et al., U.S. Pat. Nos. 4,940,503 and 5,034,272 to Lindgren et al., U.S. Pat. Nos. 5,266,384 and 5,702,806 to O'Dell et al., U.S. Pat. Nos. 5,288,540, 5,362,557, 5,456,949 and 5,558,906 to Albrinck et al., and U.S. Pat. Nos. 5,037,694, 5,093,185 and 5,037,694 to Ungar et al. all disclose decorative laminates and/or processes for preparing decorative laminates.
None of these patents disclose decorative laminates that have abrasion resistant particles with an average particle size from about 9 to about 12 microns and particle concentration of from about 2 to 4 grams per square meter of surface area. Furthermore, none of these patents disclose a process, which involves simultaneously coating: (i) the top surface or side of a dried, partially impregnated paper with an abrasion resistant coat, and (ii) the bottom surface or side of the dried, partially impregnated paper with a thermosetting resin coating. Thus, none of these patents describe the efficient process and construction of the subject low pressure laminated panel.